Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• efficiency values of 7.3%. The problem of the low solubility of such polymers was partially solved by inserting an alkylene spacer between two thiophene fragments in one of the monomer units [44]. Efficiency (3.0–3.7%) and viscosity characteristics provide good prerequisites for the use of this type of

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• design a specific range of operation and often a very specific window of optimal pumping efficiency (flow rate, pressure drop and viscosity) within this domain. Hence, especially when considering the concepts of direct scale-up this becomes an increasingly important aspect. Examples of flow systems

Nitroalkene reduction in deep eutectic solvents promoted by BH₃NH₃

• Chiara Faverio,
• Monica Fiorenza Boselli,
• Patricia Camarero Gonzalez,
• Alessandra Puglisi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2021, 17, 1041–1047, doi:10.3762/bjoc.17.83

• is a nontoxic, biodegradable and nonflammable solvent for which no special handling or storage precautions are required [19]. Some limits, such as high viscosity and low solubility of highly hydrophobic compounds and possible side reactions due to the presence of hydroxy groups, can be overcome by

Synthesis of 10-O-aryl-substituted berberine derivatives by Chan–Evans–Lam coupling and investigation of their DNA-binding properties

• Peter Jonas Wickhorst,
• Mathilda Blachnik,
• Denisa Lagumdzija and
• Heiko Ihmels

Beilstein J. Org. Chem. 2021, 17, 991–1000, doi:10.3762/bjoc.17.81

• low fluorescence quantum yields are caused by conformational changes in the excited state, the fluorescence was recorded in media with different viscosity, namely in glycerol at different temperatures (Figure 2, Figure S2, Supporting Information File 1). It was observed that the derivatives 5a–e have

• deactivation of the excited state by conformational changes, e.g., torsional relaxation [42][43]. Since the fluorescence quantum yield of the parent berberine (1a) does not correlate well with the viscosity of the medium [40], it was concluded that the weak light-up effect in glycerol is mainly caused by the

• suppressed rotation about the Ar–O bond. Nevertheless, as the emission quantum yield of the derivatives 5a–e still remained low, even at high viscosity of the medium, there obviously exist additional relaxation pathways in the excited state, most likely a photo-induced electron transfer (PET) from the 10

Supramolecular polymers with reversed viscosity/temperature profile for application in motor oils

• Jan-Erik Ostwaldt,
• Christoph Hirschhäuser,
• Stefan K. Maier,
• Carsten Schmuck and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2021, 17, 105–114, doi:10.3762/bjoc.17.11

• , 64293 Darmstadt, Germany 10.3762/bjoc.17.11 Abstract We report novel supramolecular polymers, which possess a reversed viscosity/temperature profile. To this end, we developed a series of ditopic monomers featuring two self-complementary binding sites, either the guanidiniocarbonyl pyrrole carboxylic

• concentration of the solution and on the polarity of the solvent. This effect can counteract the loss of viscosity of the solvent at elevated temperatures, thus opening an application of our systems as viscosity index improvers (VIIs) in working fluids. This was tested for different motor oils and led to the

• identification of one compound as a promising VII. Keywords: noncovalent interactions; polymers; ring-chain transformation; supramolecular chemistry; viscosity; Introduction Viscosity index improvers (VIIs) are used to counteract the loss of viscosity of working fluids (such as motor oils) at elevated

Dirhamnolipid ester – formation of reverse wormlike micelles in a binary (primerless) system

• David Liese,
• Hans Henning Wenk,
• Xin Lu,
• Jochen Kleinen and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2020, 16, 2820–2830, doi:10.3762/bjoc.16.232

• hydrophobic groups are oriented towards the solvent. One structure which can be formed by surfactants are so-called wormlike micelles, that are characterized by a high anisotropic structure. These micelles can, if the concentration and dynamics of the surfactant micelles is right, build viscosity since the

• ) gradually declines with increasing temperatures, indicating a reduction in the length of the micelles. Consequently, the shortened micelle lengths lead to a low-viscosity material at higher temperatures. The variations of G''min/G0, η0, and τR depending on the temperature are shown in Figure 7 as an

• . Rheological values obtained from the oscillatory-shear experiments for the dirhamnolipid ethyl ester 2/toluene (0.5 wt %) system at different temperatures. Supporting Information Supporting Information File 524: Synthesis of the compounds and additional Figures and Tables (viscosity). Acknowledgements The

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

• with LED strips. A pneumatic nebulizer was used. The droplet diameter was reported by the nebulizer supplier as 6 µm for water-based solutions. The droplet size depends on the surface tension and viscosity of the liquid and the pressure of the gas. Therefore, it might be different for different

• the diffusivity, kinematic viscosity, reactor volume, stirrer speed, etc. For a laminar flow in microstructured reactors, the characteristic mixing time can be calculated by the Einstein–Smoluchovski equation (Equation 6). Due to the short diffusion distances, complete mixing can be achieved rapidly

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Oligomeric ricinoleic acid preparation promoted by an efficient and recoverable Brønsted acidic ionic liquid

• Fei You,
• Xing He,
• Song Gao,
• Hong-Ru Li and
• Liang-Nian He

Beilstein J. Org. Chem. 2020, 16, 351–361, doi:10.3762/bjoc.16.34

• and green preparation processes are the two key features for the development of green products. As a bio-lubricant in metalworking fluids, estolides of ricinoleic acid are considered as the promising substitute to mineral oil with a favorable viscosity and viscosity index. Thus, an efficient and

• used as lubricant for metal cutting oils due to its appropriate viscosity, good adsorptivity and film formation ability on metal surfaces. Furthermore, the biodegradability of these estolides in the environment makes them attractive as green products. In parallel with the increasing demand for high

• changing the reaction time at 190 °C and 50 kPa with 15 wt % IL as catalyst. The viscosity characterization showed the product derived from 6 h of reaction, whose acid value is 51 mg KOH/g and the corresponding average oligomerization degree is 4, meets the requirement of lubricant additive index. Notably

p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

• Panagiotis S. Gritzapis,
• Panayiotis C. Varras,
• Nikolaos-Panagiotis Andreou,
• Katerina R. Katsani,
• Konstantinos Dafnopoulos,
• George Psomas,
• Zisis V. Peitsinis,
• Alexandros E. Koumbis and
• Konstantina C. Fylaktakidou

Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33

• cause of the activity. Therefore, the interaction of selected compounds, i.e., 11 and 12, with CT DNA was monitored by UV–vis spectroscopy and viscosity measurements. Additionally, the EB−displacing ability of the compounds was evaluated by fluorescence emission spectroscopy. The UV–vis spectra of a CT

• collected, i.e., DNA-viscosity measurements [70]. Thus, the monitoring of the DNA viscosity changes when compounds 11 and 12 are present, may be elucidating in regard to their binding mode to DNA. As known, the changes of the relative DNA viscosity (η/ηo)1/3 are proportionally related to changes of the

• relative DNA length (L/L0) [71]. Having this relation in mind, the viscosity of a CT DNA solution (0.1 mM) was determined (Figure 3) in the presence of increasing amounts of compounds 11 and 12 (up to the value of r = 0.35). For compound 11 the DNA viscosity increases in the presence of the compound. For

Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

• Afef Mabrouki,
• Malek Fouzai,
• Armand Soldera,
• Abdelkader Kriaa and
• Ahmed Hedhli

Beilstein J. Org. Chem. 2020, 16, 149–158, doi:10.3762/bjoc.16.17

• in organic chemistry [3]. The C–F bond is highly polarized and this polarity inhibits the lone pair donation from fluorine, making this element a weak coordinator. These properties are the basis for the unique properties of perfluoroalkylated compounds such as high viscosity, high density, high

• lead on a deep study in order to investigate other parameters such as response time, viscosity and dielectric anisotropy. DSC thermograms of fluorinated compounds 2b, 4a and 4b recorded at 5 °C/mn at heating (down traces) and cooling (top traces) cycles. Optical texture (×10) of liquid crystal phase

Fabrication, characterization and adsorption properties of cucurbit[7]uril-functionalized polycaprolactone electrospun nanofibrous membranes

• Changzhong Chen,
• Fengbo Liu,
• Xiongzhi Zhang,
• Zhiyong Zhao and
• Simin Liu

Beilstein J. Org. Chem. 2019, 15, 992–999, doi:10.3762/bjoc.15.97

• loadings influences the morphology and AFD of the resulting electrospun nanofibers. The variations in AFD of the PCL/CB[7] nanofibers are attributed to differences in electrical conductivity and viscosity of the polymer solutions [13][14][15]. FTIR spectroscopy is a frequently used and effective method to

Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines

• Andrejs Šišuļins,
• Jonas Bucevičius,
• Yu-Ting Tseng,
• Irina Novosjolova,
• Kaspars Traskovskis,
• Ērika Bizdēna,
• Huan-Tsung Chang,
• Sigitas Tumkevičius and
• Māris Turks

Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41

• solvent properties such as viscosity or hydrogen bonding. Interestingly, purine class compound 8c showed a dual-fluorescence character in the solvents of higher polarity (DMSO, MeCN) arising from the locally excited and charge transfer excited states, however, dual-fluorescence was not evident for the 7

• excited states are environment-dependent it makes these fluorophores interesting as potential sensors of the surroundings such as polarity or (micro)viscosity sensors. Other purine and 7-deazapurine derivatives, which efficiently emit light in the blue region with respect to the structural

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• can significantly improve such properties of the polymer as thermal and oxidative resistance, surface properties, improvement of mechanical properties as well as reduced flammability, heat release and viscosity during processing [29]. Synthesis, properties and applications of POSS-containing materials

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• by light scattering [90]. Another possible concern is related to the high viscosity of the initial polymer mixture, especially in the case of high molecular mass components, like PNB. Fortunately, upon the catalyst addition such mixtures rapidly become more fluid because of polymer-chain scission

Adhesion, forces and the stability of interfaces

• Robin Guttmann,
• Johannes Hoja,
• Christoph Lechner,
• Reinhard J. Maurer and
• Alexander F. Sax

Beilstein J. Org. Chem. 2019, 15, 106–129, doi:10.3762/bjoc.15.12

• , and for many properties such as boiling point or viscosity of liquids. Basics of Weak Molecular Interaction Description of interaction through forces and potentials Interactions in a system consisting of two or more subsystems cause changes of the spatial positions of the subsystems relative to each

Fabrication of supramolecular cyclodextrin–fullerene nonwovens by electrospinning

• Hiroaki Yoshida,
• Ken Kikuta and
• Toshiyuki Kida

Beilstein J. Org. Chem. 2019, 15, 89–95, doi:10.3762/bjoc.15.10

• realizes easy handling of inclusion complexation with guest molecules as well as electrospinning due to the much lower viscosity of the CD/HFIP solution. The formation of a 2:1 inclusion complex should not affect the solution properties (e.g., viscosity and solubility), but should provide electrospinning

• is essential. Association is predicted from the relationship of the solution viscosity and concentration [6][9][11]. As reported previously, the increased rate of viscosity with the concentration in γ-CD/HFIP solution clearly becomes larger at 10–15 w/v %, indicating intermolecular associations of γ

• -CD molecules in HFIP [11]. Interestingly, no significant viscosity differences are observed after C60 addition into γ-CD/HFIP solution (Figure S4 in Supporting Information File 1). This is important from the viewpoint that the solution properties are governed by the intermolecular interactions

Dynamic light scattering studies of the effects of salts on the diffusivity of cationic and anionic cavitands

• Anthony Wishard and
• Bruce C. Gibb

Beilstein J. Org. Chem. 2018, 14, 2212–2219, doi:10.3762/bjoc.14.195

• Boltzmann constant, T is the temperature, η is the viscosity of the solution, and rH is the hydrodynamic radius. In all cases, at the initial 20 mM concentration of NaOH the light scattering induced by 1 was weak. This resulted in relatively flat autocorrelation functions generated from the measured

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

• absorption spectroscopy, viscosity measurement, cyclic voltammetry and molecular modeling (Figure 9) [93]. Docking results confirmed that these complexes have the ability to interact with the minor groove of the ct-DNA. In addition, the authors confirmed that in presence of ascorbic acid, these complexes

Mechanochemistry of nucleosides, nucleotides and related materials

• Olga Eguaogie,
• Joseph S. Vyle,
• Patrick F. Conlon,
• Manuela A. Gîlea and
• Yipei Liang

Beilstein J. Org. Chem. 2018, 14, 955–970, doi:10.3762/bjoc.14.81

• POCl3 (e.g., Scheme 10), monoalkyl phosphorodichloridates or dialkyl phosphoromonochloridates in the absence of solvent has been reported [48]. Migaud and co-workers prepared highly water-sensitive phosphitylating agents directly from PCl3 in low viscosity ionic liquids derived from the tris

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions

• Kendra Leahy Denlinger,
• Lianna Ortiz-Trankina,
• Preston Carr,
• Kingsley Benson,
• Daniel C. Waddell and
• James Mack

Beilstein J. Org. Chem. 2018, 14, 688–696, doi:10.3762/bjoc.14.57

• formation of this bond may have a large influence under mechanochemical conditions because there is not a solvent reservoir to accept the dispersion of these ions. Using Pearson’s hard and soft acid and base (HSAB) theory [29] and the Jones–Dole viscosity B coefficient [30] (Table 3), we can predict which

• alkali metal and halide pairs would be most favourable. For example, bromide is a borderline soft anion, so based on the proposed mechanism we would expect more product to form if the counter ion is Cs+(soft) than if it was Li+ (hard). Using the Jones–Dole viscosity B coefficient, we could also predict

• higher E selectivity was obtained. The high concentration of reactants under mechanochemical conditions allows for unique and potentially selective reactions that may not be achievable by traditional synthetic means. Further studies on the influence of HSAB theory and the Jones–Dole viscosity B

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• techniques like electronic spectra, viscosity measurement and thermal denaturation. Ahmetaj et al. [105] described a simple and efficient protocol for the synthesis of 7-heteroarylpyrazolo[1,5-a]pyrimidine-3-carboxamides 166 from the reaction of 5-aminopyrazole 161 with (E)-3-(dimethylamino)-1-(heteroaryl

Synthesis and supramolecular properties of regioisomers of mononaphthylallyl derivatives of γ-cyclodextrin

• Markéta Bláhová,
• Sergey K. Filippov,
• Lubomír Kováčik,
• Jiří Horský,
• Simona Hybelbauerová,
• Zdenka Syrová,
• Tomáš Křížek and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2017, 13, 2509–2520, doi:10.3762/bjoc.13.248

• regioisomers in similar ways as González-Gaitano [21] and as we did for Cin-α-CD [20]. The temperature was raised from 5 °C to 65 °C (5 °C steps) across 2.5 h, which led to substantial changes in sizes of the aggregates (Figure 3). A shift of the correlation curve, caused by the change of viscosity, is

One-pot three-component route for the synthesis of S-trifluoromethyl dithiocarbamates using Togni’s reagent

• Azim Ziyaei Halimehjani,
• Martin Dračínský and
• Petr Beier

Beilstein J. Org. Chem. 2017, 13, 2502–2508, doi:10.3762/bjoc.13.247

• fields of pharmaceuticals, agrochemicals, and materials sciences. The key properties such as metabolic and chemical stability, polarity, bioavailability, viscosity and lipophilicity can be altered in molecules containing the CF3 group in comparison with the nonfluorinated analogues. Numerous methods have

Hydrolysis, polarity, and conformational impact of C-terminal partially fluorinated ethyl esters in peptide models

• Vladimir Kubyshkin and
• Nediljko Budisa

Beilstein J. Org. Chem. 2017, 13, 2442–2457, doi:10.3762/bjoc.13.241

• aqueous phosphate buffer (right, 50 mM buffer, pH 7.0) samples. Recorded at 298 K and 100 μM peptide. Conformational analysis of the peptides by 1H DOSY NMR (D2O, 298 K). The theoretical values were calculated according to Equation 5 assuming deuterium oxide viscosity and 298 K. Hydrolysis of the C